GM Service Manual Online
For 1990-2009 cars only

Step

Action

Values

Yes

No

1

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

Inspect fuse F6 in the I/P fuse block.

Is this fuse in good condition?

--

Go to Step 4

Go to Step 3

3

Replace the fuse F6.

Is the repair complete?

--

System OK

--

4

Inspect fuse EF6 in the engine fuse block.

Is this fuse in good condition?

--

Go to Step 6

Go to Step 5

5

Replace the fuse EF6.

Is the repair complete?

--

System OK

--

6

  1. Turn ON the ignition, with the engine OFF.
  2. Measure the voltage between the ground and the terminal 87 of the blower relay.

Is the voltage within the specified value?

11-14 V

Go to Step 14

Go to Step 7

7

Measure the voltage between ground and terminal 86 at the blower relay.

Is the voltage within the specified value?

11-14 V

Go to Step 9

Go to Step 8

8

  1. Turn ON the ignition, with the engine OFF.
  2. Inspect circuit between terminal 86 of the blower relay to F6 in the I/P fuse block.
  3. Repair any problem found in the wiring or terminals at the relay socket or connector C201.

Is the repair complete?

--

System OK

--

9

Measure the voltage between ground and terminal 30 at the blower relay.

Is the voltage within the specified value?

11-14 V

Go to Step 11

Go to Step 10

10

  1. Turn ON the ignition, with the engine OFF.
  2. Inspect circuit between terminal 30 of the blower relay to EF6 in the engine fuse block.
  3. Repair any problem found in the wiring or terminals at the fuse block connector C106, connector C208, or at the relay socket.

Is the repair complete?

--

System OK

--

11

  1. Turn OFF the ignition.
  2. Inspect the continuity in the wiring harness between the blower relay terminals 85 (BLK) and ground.

Does the ohmmeter show the specified value?

0 ohms

Go to Step 13

Go to Step 12

12

Repair any problem found in terminal 85 at the relay connector, circuit, splice S201, or ground G202.

Is the repair complete?

--

System OK

--

13

Replace the blower relay.

Is the repair complete?

--

System OK

--

14

  1. Turn OFF the ignition.
  2. Disconnect the wiring harness at the blower motor.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage between the ground and the blower connector 1.

Is the voltage within the specified value?

11-14 V

Go to Step 16

Go to Step 15

15

  1. Turn OFF the ignition .
  2. Inspect circuit between blower connector terminal 1 and blower relay terminal 87.
  3. Repair any problem found in the wiring or a connector terminal at the blower connector, connector C217, or the blower relay socket.

Is the repair complete?

--

System OK

--

16

Measure the resistance between the connector terminals on the blower motor.

Does the resistance equal the specified value?

5 ohms

Go to Step 18

Go to Step 17

17

Replace the blower motor.

Is the repair complete?

--

System OK

--

18

Measure the resistance of circuit between terminal 2 of the blower connector and terminal 30 of the Max HI relay and terminal 6 of the power transistor.

Does the resistance equal the specified value?

0 ohms

Go to Step 20

Go to Step 19

19

Repair the problem in circuit.

Is the repair complete?

--

System OK

--

20

Measure the resistance of circuit from terminal 3 of the power transistor connector to ground.

Does the resistance equal the specified value?

0 ohms

Go to Step 22

Go to Step 21

21

  1. Trace circuit from terminal 3 of the power transistor connector and terminal 87 of the Max HI relay to ground G201.
  2. Repair any problem found in the wiring, ground G201.

Is the repair complete?

--

System OK

--

22

Replace the automatic temperature controller (ATC). Refer to Heater and Air Conditioning Control Replacement .

Is the repair complete?

--

System OK

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